Abraham Lincoln's stovepipe hat is part the Taper Collection, which the Abraham Lincoln Presidential Library and Museum has acquired.
(AP)

The Abraham Lincoln Presidential Library and Museum is re-displaying a stovepipe hat synonymous with the country’s 16th president, amid renewed speculation about its authenticity.

The purported $6.5 million hat is being put on display to mark Lincoln’s 204th birthday.

Questions about the origin of the iconic hat were raised last spring by the Chicago Sun-Times.

The description next to the hat reads that only three of the stovepipe hats are known to exist "two silk ones from his last days of life, and this."

The newspaper says the museum makes no mention that Illinois officials cannot prove whether the hat belonged to Lincoln or whether the story about him giving this one to a southern Illinois farmer is real.

The museum did not respond to a FoxNews.com request for comment but told the newspaper: "There's no deception at all."

There appears to be no disputing the hat is real.

The hat bears the stamp of a 1850s-era Springfield, Ill., hat maker, stayed in the possession of the same southern Illinois family for a century and is the same size as Lincoln’s.

However, officials at the Springfield, Ill., library and museum acknowledged last year that they were not sure, more than 150 years ago, how a farmer acquired the hat.

The hat stayed in the possession of the farmer’s family until 1958. Then James Hickey, then head of the Illinois State Historical Library and overseer of the state’s Lincoln artifacts, bought it for himself.

The newspaper said such a move today “would almost assuredly spark conflict-of-interest questions.”

Lincoln collector Louise Taper bought it from Hickey in 1990 for an undisclosed price. Then she sold it in 2007 to the Abraham Lincoln Presidential Library Foundation as part of a $23 million deal for Lincoln memorabilia.

The foundation then began raising money to repay the city of Springfield, which issued taxpayer-financed bonds to buy the collection.